Attachment plug



E. J. SCHUTT ATTACHMENT PLUG Jan. 28, 1930.

Filed April 11. 1927 E'm/ett 14 W AQW Patented Jan. 28, 1930 PATENT; OFFICE EHKET'I. J. SCHUTT, OI RAMSEY, NEW JERSEY ATTACHIENT PLUG Application filed April l l,

This invention relates primarily to a quick detachable plug and cap for connecting electric apparatus to an electric circuit.

The usual form of quickly detachable connections used for domestic as well as other purposes, essentially comprises a receptacle in the form of an attachment plug, or base, having spaced recesses in which are protectively and insulatingly secured spring contacts and a plug cap. The plug cap can be connected in the usual way to an electric light outlet, or other electric apparatus connected to an electric circuit. The cap has two spaced terminal posts or blades designed for inser- 5 tion in the plug recesses for electrically contacting with the spring contacts in the plug recesses. Considerable difliculty is frequently experienced in inserting the cap terminal posts or blades into the plug recesses. Some-v il0 times a novice, or other person who has had no previous experience with electrical appliances, will attempt to insert the cap posts mto the plug recesses at an angle, and W111 find that some obstructing part will prevent such haphazard insertion. More often, one will find it exceedingly difficult to initially enter both posts at the same time into the plug recesses since the posts are quite frequently spaced a distance substantially equal to the distance between the adjacent walls of the plug recess, or nearly so, so that if the cap posts or blades are not carefully and more or less equally inserted or introduced into the plug recesses, one will find that one post will enter its recess and the other will be deflected or obstructed from entering its recess. More especially is this true where an unsteady hand is attempting to effect the desired electrical connection. In instances where the plug or base is permanently fixed. as in a wall, floor, or ceiling, it is diflicult for one to have a clear view of the plug and especially its recessed openings, by reason of its more Or less inaccessible position or 10- 4 cation, and it therefore requires considerable manipulation with the consequential annoyance and worry to the individual before the desired electrical connection has finally been established.

Various attempts have been made to pro- 1927. Serial No. 182,844.

vide a connector of the quick detachable type for facilitating the introduction of the ca posts or blades into the plug recesses, suc as by flarin the walls of the individual recesses, whic do, more or less, accomplish their desidei'atum, but they fall short of totally avoiding the disadvantages of the usual plug, and necessitate nearly as much, if not as much, manipulation on the part of the user to effect the proper insertion of the cap posts.

The present invention is desi ed to facilitate and expedite the connection of electrical apparatus by the use of connectors of the above described quick detachable type, and it has for its objects to provide a con- 05 nector in which the cap posts or blades will be introduced into their plug recesses with a minimum eflort on the part of the user; to provide a plug art in which the cap will be self-centered relatively to the plug, and the posts or blades more or less automatically directed into the plug recesses; to provide a detachable connector wherein the cap posts will be insured entering the plug recesses by and during an inserting movement of the cap in a direction toward the plug, with or without a single added manipulative movement of the cap, which added movement is the only possible manipulative movement on the part of the user; to provide a plug member with an annular channel or depression in its face, into which channel or depression the plug recesses open, which channel or depression will guide the cap terminal posts in a direction to insure ultimate finding of the plug recesses upon imparting a rota movement to the cap; to provide such annu ar channel in the plug face with upwardly or outwardly flaring walls for guiding the cap posts to the bottom of the channel; to provide a plug in which the por- 00 tion of the plug face between the plug recesses is provided with a knob or button of a maximum diameter substantially equal to the minimum distance between said plug recesses; and to provide a plug member in which said knob or button is of a dome shape, or an upwardly or outwardly tapering contour.

The invention further has for an object the provision of an illuminated portion for 1 0 facilitating the proper centering of the cap posts relative to the plug recesses when the plug is in a darkened area, or at night, as well as to provide a knob or button provided with a luminous material or the like, which knob with its luminous material is substantially round and of a diameter substantially filling the space between the plug recesses.

The invention is found to reside in the salient features of construction and the arran ements and combinations of parts hereinafter described in detail and succinctly claimed, reference being made to the accompanying drawings, wherein,

Fig. 1 is a view, partly in section, of the quick detachable connector embodying the present invention.

Fig. 2 is a plan view of the receptacle or plug member.

Fig. 3 is a sectional view about on line 33 of Fig. 2.

Fig. 4 is a view similar to Fig. 1 depicting a modification of the invention.

Fig. 5 is a perspective view showing the manner of applying the cap to the plug.

Fig. 6 is a view showing the invention incorporated in a wall, floor or ceiling recep tacle.

Fig. 7 is a plan view of another slightly modified form of the invention, the cap posts being in section.

Referring more in detail to the accompanying drawings, the numeral 1 designates the detachable plu cap of a quick detachable connector assem ly, the cap embodying a pair of contact posts or blades 2 projecting from the under side of the cap in substantial parallelism for insertion into the recesses 3 of a receptacle or plug member 4. This cap is usually attached to a cord 5, which cord consists of two circuit wires connected at their opposite ends to an electrical apparatus of some form or other not shown. The plug recesses 3 are formed at spaced points in the insulating material from which the plug member 4 is formed, and in the lower portion of each recess is disposed the usual contact spring 6 which ma be of a preferred or desired form. The p ug member may be of any particular style, such as the removable threaded type, designated in Figure 1, or it ma be of a permanently fixed type such as a wa l receptacle or plug, as indicated in Figure 6, such as may be found at convenient and accessible points throughout a dwelling, in the flooring, the baseboard, or the wall at a convenient height above the floor. The recesses 3 may be rectangular in cross section, or they may be T-shaped in cross section for universally accommodating plugs in which the terminal blades 2 are parallel to each other as well as those in which the parts or blades are disposed in the same planar relation.

The outer face of the plug body 4, or that face which is exposed to receive the terminal posts 2, is provided with an annular groove 7 through the base of which the recesses 3 open at substantially diametrically opposite points. The resultant and circular sectioned central knob or button 8 within the annular groove preferably has its surface convexed or of dome shape, the base of the knob having a maximum diameter substantially equal to the minimum distance between the two re- 3, when they reach the bottom of the groove, 7

they will readily come to such entering position upon rotating the cap in either clockwise or counter-clockwise direction. The knob 8 consequently centers the cap 1 relative to the recesses 3 and, being axially centered, it will be obvious that any rotated movement will permit the posts to readily find the recesses, since any rotated movement of the cap must of necessity be in an are or in an arcuate path which includes said recesses 3, this being insured by the knob 8. Thus the groove 7 provides relatively concentric, arcuate guideways, the inner walls of the guideways comprising the centering knob 8. In this connection it will be noted that the base of the knob, which constitutes the inner wall of the annular groove, or the inner wall portions of the arcuate guideways, rises abruptly from the recesses 3, or in other. words, the knob provides an abrupt guide shoulder which rises immediately from the circular path of the terminal posts 2 in which path is located the recesses 3. The opposite portions of the thus provided guide shoulder are relatively concentric and of substantially the same radii, and consequently lead directly to said recesses. The spacing of the inner wall or shoulder portions of the arcuate guideways is therefore substantially equal to the spacing between the recesses 3 so that the posts 2 when engaged with said inner wall portions will be confined to a definite rotary path leading directly to the recesses. Said inner wall portions rising abruptly from and immediately adjacent the inner side of the circular path including said recesses eliminates any loose and unguided movement of the posts and thereby insures the posts finding the recesses by purely rotary, manipulated movement otherwise unguided by the operator or person making the electrical connection.

The outer wall of the groove 7 is-fiared outwardly, preferably formed with a lower,

slightly concaved, portion 9 and an u per, slightly convexed, portion 10, the latter cading to an annular shoulder 11 which surrounds the marginal portion of the outer face of the plug member. The convexity 10 cooperates with the remote convexity ofthe knob 8 in facilitating the guiding of the posts 2 into the bottom of the annular groove or channel 7. Especially is this true when the cap is applied annularly to the plug with one post engaging the convexity 10 and the companion post engaging'the domed top of the knob 8. This relationship is substantially shown in Figure 4 and from which it will be obvious that relative closin movement between the cap and the plug Wlll effect a riding down upon the respective convexities by the two posts, with the ultimate axial alignment of the two component parts of the connector. When so axially aligned the two posts will engage the bottom of the groove 7, and if in registry with the recess will of course enter the same as suggested by the dotted showing in Figure 4. However if registry is not obtained by this initial placement, a slight rotary movement ofv the cap in one direction or the other, as indicated in Fig. 5, will bring the posts into registry with the recesses for a further, axial movement. To further facilitate the entering of the posts into the recesses the opposite end corner of the rectangular recesses 3 may be rounded as at 12, so that when the posts are moving around in the channel or grooves 7, as when the cap 1 is rotated, they will ride very easily from the bottom of the groove over the rounded edges 12 down into the recesses 3. The cap posts may be curved in cross section, as indicated at 2 so as to hug or conformably engage the knob, the recesses 3' preferably conforming in curvature to the posts 2'. Thls conformable engagement :of the posts with the knob substantially holds the posts against lateral displacement from the knob. By applying a luminous material to the knob 8 the finding of the plug at night is greatly facilitated. This is more clearly accentuated in Figure 4 wherein is disclosed a modification of the invention. In this showing the knob or button 8 has been replaced by a luminous knob or button 14, this preferably consisting of a glass dome having a stem portion 15 adapted to be cemented in, cast with or secured in a recess 16 formed in the portion of the body 4 between the recesses 3. This glass dome is preferably treated on the inside, as indicated at 17, with a luminous materlal so as to facilitate the finding of the plug in the dark or at night. The knob or button may be of a solid luminous body cemented in, cast with or secured in the recess 16. In this form of the invention the glass dome or other solid luminous body is substantially of the same shape as the knob 8, and the luminosity offered by the coated surface 17 covers an area and disposes them within a circle in the circumference of which is arranged the two recesses 3. The central knob may be below the surrounding marginal shoulder 11, of equal height, or it may project above the plane of said shoulder in which latter instance the projecting portion will be received by the cap. The provision of the central knob with its surrounding outwardly flared wall insures an almost automatic insertion of the terminal posts 2 in their recesses even though the cap 1 is applied to the plug member at an angle or off center. The outwardly flaring wall extends radially outward beyond the recesses 3 so as to provide a broad guiding surface or area around the centerin knob 8 so that the cap posts 2, when engage with this flaring, guiding surface, will be laterally or radially uided inwardly against the centering knob whereby a purely rotative movement will cause the posts to find their recesses. The posts are prevented from binding on the outer wall of the groove by reason of the flare of the latter, which flare provides ample clearance to avoid the longitudinal corners of the posts engaging said outer wall in any manner which might cause a binding action during the rotative movemet of the posts about the centering knob. By means of the annular groove into which opens the recesses 3, the user is materially assisted in insorting the posts into their circuit closing position, since by disposing said posts within the groove the only possible manipulative movement is a rotative one and such rotative movement will of necessity cause the posts to find the recesses. With the central knob projecting from the plug member the posts are held against lateral play from the circular path in which the recesses are located and consequently rotative motion around the knob will bring the posts to their recesses. In the form of the invention shown the outer wall of the groove prevents lateral, straddling displacement of the posts from the knob. The marginal annular shoulder 11 further tends to restrict lateral playandconfines the posts to the face area of the plug member, should the cap member be only lightly applied during its initial insertive movement. The knob will be found to be a sustaining spacer for the cap posts, holding them properly spaced. This is especially advantageous wherein the posts loosely incline toward each other or are bent toward each other. Should their free ends be normally spread apart, their contact with and riding down on the flared outer wall 9, 10 will bring them to a proper spacing at the bottom of the oove 7 the outer wall of which flares from t e recesses 3. Should the inner edge of a post contact with the domedknob it will glancingly deflect or ride thereon down into the groove, as indicated in Fig. 1. The distance between the outer edge of one post and the inner edge of the companion post is slightly greater than the distance between the inner side of shoulder 11 and the apex or central point of the knob 8, or 14, so that with one post abutting the inside of shoulder 11 the other post will engage the remote convexity of the knob and tend to shift the cap into axial alignment with the plug.

I claim v 1. In a quick detachable connector, an attachment plug comprising a body of insulating material having spaced recesses, contact elements arranged in the recesses, said recesses opening through one face of the body, and said contact elements being disposed within said recesses a distance from said face, said face having an annular groove in the circumference of which open said recesses, the outer wall of said groove flaring outwardly and havingan inner concave portion merging into a outer convex portion for guiding the posts of a plug cap down into the bottom of the groove, the inner wall of said groove defining a centrally disposed knob with a base diameter substantially equal to the minimum distance between the recesses,

said knob tapering outwardly.

2. An attachment plug comprising a body having an annular groove in its outer face and spaced recesses opening into the bottom of the groove, and contact elements arranged within the recesses, the inner wall of the groove rising abruptly from the inner marginal portions of said recesses.

3. An attachment plug comprising a body of insulating material having spaced recesses opening through its outer face, a circular centering knob on the outer face of the body disposed between the recesses and having a maximum diameter substantially equal to the minimum distance between the recesses, and a wall concentric to and spaced outwardly from the knob and recesses for preventing lateral displacement of the posts of a plug cap from off the knob during the act of in serting the cap posts into'the recesses.

4. An attachment plug comprising a body of insulating material having spaced recesses opening through its outer face, contact ele ments arranged in the recesses inwardly from near the outer ends of the recesses, the outer face of said body being dished to provide an annular flaring wall about the spaced recesses, said outer flaring wall flaring directly from the recesses, and a round-domed tion merging into an outer convex portion for guiding the posts of a plug cap down into the bottom of the groove, the inner wall of said groove defining a centrally disposed knob, and a marginal wall upstanding from the convex portion of the outer wall of said groove;

6. An attachment plug comprising a body of insulating material having spaced recesses opening through one face, a centering knob formed on the face between the recesses having a maximum diameter substantially equal to the minimum distance between said recesses.

7. An attachment plug comprisin a body of insulating material having space contact recesses opening through one face, said face having an annular groove into which open said recesses, said recesses flaring into said groove, said groove being otherwise continuous and uninterrupted throughout, and the annular inner wall of the groove rising abruptly from and constituting substantial continuations of the inside edges of the recesses.

8. An attachment plug comprising a body of insulating material having spaced contact recesses opening through its face, and relatively concentric arcuate guideways in said face leading to said recesses and acting to properly space and center the posts of a plug cap relative to said recesses, the inner wall portions of the arcuate guideways providing abruptly rising guide shoulders concentrically related and leading to said recesses.

9. In a quick detachable connector, an attachment plu comprising a body of insulating material aving spaced recesses, contact elements arranged in. the recesses, said recesses opening through one face of the body, and said contact elements being disposed within said recesses a distance from said face, said face having an annular groove in the circumference of which open said recesses, the outer wall of said groove flaring outwardly and having an inner concave portion merging into an outer convex portion for guiding the posts of a plug cap down into the bottom of the groove, the inner wall of said groove defining a centrally disposed knob.

10. An attachment plug comprising a body of insulating material having spaced contact recesses opening through one face, and a knob on theface between said recesses, a portion of said knob bearing luminous material.

11. A plug body of insulating material having spaced contact recesses opening through its outer face and a centering knob disposed between the recesses on the outer face, said knob being of circular form and having a maximum diameter substantially equal to the distance between the recesses and means formed on the outer face of the body for preventing lateral displacement of cap posts from said knob.

12. An attachment plug comprising a body of insulating material having in one face an annular groove into the bottom of which open spaced contact recesses, the inner wall of the groove rising abruptly from the inner edges of the recesses, and the outer wall of the groove flaring outwardly beyond and about the recesses. 1

13. A plug body of insulating material having spaced contact recesses opening through its outer face and a centering knob disposed between the recesses on the outer face, said knob being of circular form and having a maximum diameter substantially equal to the distance between the recesses, said knob comprising a glass dome on the inner side of which is a luminous material.

14. In combination, a plug'body of insulating material having on one face a round knob at the bottom of which opens spaced contact recesses of arcuate cross section, and a plug cap having spaced posts curved in cross section to conformably en age the knob and movable in a circular path a out the knob for directing the posts to a position to be received by the recesses.

15. In a separable electric plug, the combination of a plug body' having a pair of contact members spaced apart therein, parts on said plug body extendmg outwardly beyond said contact members and having surfaces extending continuously around the peripheral margin of said body and inclined from said margin inwardl toward said contact members and adapte to receive and tact blades of a separable cap or said plug to contact or circuit-closing positions with said contact members upon movement of said cap toward said plug and angular turning movement of said ca about the axis of said plug in either directlon, and a knob of insulating material positioned substantially centrally between said contact members and extending outwardly therefrom, said knob having inclined outer sides, the adjacent sides of said inclined plug body'parts and said knob divergin outwardly and the sides of said inclined p ug body parts and the corresponding remote sides of the knob extending substantially parallel one to the other whereby the sides of the knob cooperate with the inclined sides of the plug body in guiding the posts, said recesses being located at the base of said knob within the defined post-path, the portion of said face about said knob flaring outwardly therefrom to provide a laterally-guiding surface for deflecting the posts of the plug part radially inward against the centering knob whereby the posts will find said recesses upon rotary. movement of the plug part relative to the receptacle, said flaring portion providing clearance for the posts to avoid any binding of the same on said portion of the face.

17. A member having electric contacts in spaced sockets adapted to receive parallel spaced prongs of a terminal member and having its receiving face annularly grooved, these sockets opening into the bottom of the groove so that the walls of'the groove present sloping co-axial guiding faces to the prongs.

' EMMETT J. SCHUTT.

ide the con- 7 CERTIFICATE OF CORRECTION.

Patent No. 1,745,233. Granted January 28, [930, to

EMMETT J. SCHUTT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 103, for the misspelled word "movemet" read "movement"; page 4, line 100, claim 7, after the word "throughout" insert the words "the outer wall of the groove flaring upwardly from the groove bottom"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 4th day of March, A. D. 1930.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

